Pulp screen and washer



` March 2, 1943.

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yMau-sh 2, 1943. vc. scHEiDlNG PULP scREEN'AND 'WASHER- 8 Sheets-Shed 8 Filed Dec. 8, 1939 Patented Mar. 2, 1943 PULP SCREEN AND WASHER Carl Scheiding, Middletown, Ohio, assignor of one-half to F. C. Zart, Cincinnati, IOhio Application December 8, 1939, Serial No. 308,275

3 Claims.

This invention relates to an apparatus useful in the paper industry for screening and washing Paper pulp.

Among the objects of the invention is the provision of a machine of this character which is capable of a higher production per unit area of floor space occupied and embodies continuous operation and automatic plate cleaning. Referring to the drawings,

Figure 1 is a side elevation of the righthand end of the machine, i. e., that end into which the paper pulp to be screened is introduced.

Figure 2 is a corresponding view of the left end of the machine.

Figure 2a is a full face view of one of the cross-strips of a screening unit, an intermediate portion being omitted;

Figure 2b is a transverse cross-sectional view through the cross-strip of Fig. 2a, taken on the line 2b-2b of that figure;

Figure 3 is a plan view of the righthand end of the machine corresponding to Fig. 1;

Figure 4 is a plan view of the lefthand end of the machine corresponding to Fig. 2;

Figure 5 is a transverse cross-sectional View through the machine taken on the line 5--5 of Fig. 2;

Figure 6 is a side view of a screening unit;

Figure 6a is a plan view of the screening unit of Fig. 6;

Figure'b is an end view of the screening unit of Figs. 6 and 6a.;

Figure 6c is a detailed cross-sectional view of one of the two roller-carrying shafts provided at each end of a screening unit;

Figure '7 is a fragmentary plan view of the means for delivering pulp slurry to and spreading it over the screening units;

Figure '7a is a cross-sectional view on the lineV Ia-1a of Fig. 7;

Figure 8 is a fragmentary plan view of the lefthand end of the machine showing the rotary scraping and residue ejecting means;

Figure 8a is a vertical cross-sectional View through the machine on the line Ila-8a. of Fig. 8.

In the drawings, I and 2 are substantial pedestals supporting the frame 5 of the machine. The Dedestals I and 2 support anti-friction bearings 6 and 9. The latter are movable by means of a take-up device I5 for the chain drive by which the position of the shaft I4 of sprocket |32 can be longitudinally shifted. It is, of course, to be understood that there are two similar sprockets upon each side and each end of the machine, making four in all. Over these sprockets a large endless chain, made up of links and rollers 46 and 48, is mounted. There are, of course, two such chains, one traveling over each pair of sprockets, so that each link is in horizontal alignment with the corresponding link on the other chain. Between said chains, screening units or containers 40 are carried, as can best be seen in Figures 3 and 5. As shown in Figures 6, 6a and 6b such screening units are of substantially box-like shape having a foraminous top 88 and a exible floor 56 slanting toward a bowl shaped discharge port 44 at one end. Each unit is provided with four stepped carrying shafts 45 which shafts are utilized as studs holding the links 46 together. Therefore the units 40 actually form part of their own carrying chain. Figure 6c shows a shaft 45 assembled to carry a roller 48 over whichv the chain links 46 are fitted. The nuts 50 retain the assembly. Each unit 40 is also provided with a cross strip 5I of rubber or the like to fill the space between the units and thereby to assist in the maintenance of a liquid level of pulp slurry over the continuous platform formed by the series of units 40. As can be seen in Figure 5, the flexible oor of the units is provided with a central metallic plate 59 by means of which the oor may be oscillated.

The oscillating means will now be described. An I beam 68 traverses the machine longitudinally under the middle line of the series of units 40 which together make up what may be termed a screening or filtering conveyor. See Figures l and 5. On the I beam is carried a strip 61 to which is fastened a scalloped rack 66. Each unit 40 carries attached to its plate 51 a foot 65 which bears a roller 64, said roller being adapted to fit the scallops of rack 66. Foot 65 comprises a plate carried by two studs 6I which are in turn attached to plate 59 mounted upon the bottom face of the flexible floor 56 and connected through the fioorto the plate 51. Plate 60 floats on studs 6I being maintained by a nut threadedly engaging another stud 62 which fits inside stud 6I. Springs 53 about each stud 6I pressplate 60 downward into engagement with rack 66 by means o-f roller 64. The high points of rack '66 therefore create a shock resulting in an oscillation transmitted by roller 64, foot 65, plate 60 and springs 63 which decrease the violence of the shock transmitted to plate 51 which isr'attached to the flexible floor of unit 40, thereby exerting a hydraulic action on the` liquid contents of unit 40 and afterthe manner of a diaphragm pump, pumping the liquid and solid matter up and down through the perforations of the foraminous plate 83. This action prevents the clogging of the slits or holes of said plate by particles too big to pass through them.

Referring now to Figure 5, 4| is a deflector plate mounted on the deeper side of the interior of a unit 40 so as to depend into the bowl 42 of the discharge port 44. The latter travels within a trough |20 which extends the length of the machine and which is mounted on a bracket |2| carried on an adjustable standard |22 which is bolted to cross beam l2 by means of base |23. Trough |20 is arranged to deliver its liquid contents into screened pulp discharge pipe |26. As` can be seen from Figures 5 and 6, there is a small bypass port c in the wall between spout 44 and bowl 42. This allows gradual drainage of small quantities of liquid. Since the container perforations have a greater open area than thedischarge opening 44 the contents of the container will always remain inside the latter until the container is tipped when it passes over the sprocket at the discharge end of the machine and then the small quantity of liquid remaining in bowl 42 will be emptied by bypass c. The containers 40, after being inverted to pass through the lower part of the machine on their way back to the starting point will then be substantially empty of liquid although their screens will require cleaning.

Referring again to Figures 1, 2 and 3, it will be seen that the chain of units 40 is drawn along a bar 35 with which the rollers 48 Vmake Contact. The 'bars in turn are supported by bracketsv36 which are attached to standards I0 and In this way a flat surface of screens 88 is main-- tained by preventing the sagging of the' chain which carries the screen units 40.

The means employed for delivering and spreading pulp slurry to the screening surfaces |58` will now be described. Referring to Figure l, Il is a slurry box to which liquid pulp is being. continuously delivered. A dam i9 is provided in this boX over which an eveny flow of slurry occurs. This flow then descends over a cascade seal. The latter comprises an angled body 18 which is hinged to the floor of box by means of hinge 8| and pin 82. A smooth rubber pad 80 extends over the hinge so as to prevent the latter from being clogged with pulp. A rubber sealing apron i9 iits between body 1x8 and the foraminous surfaces 88 and so assists in maintaining a liquid level over said surfaces. In order to keep the rubber T9 firmly in contact with the surfaces 88, a rod 84 is provided which cooperates with a hinge 03. The hinge is attached t0 the rear of body 18 and rod 84 is placed under tension with a spring 86 and handwheel 81 as shown in Figure` 7a. Of course, as many rods 84 may be provided as are necessary. Flexible rubber dams 28 and 2| may be providedY to settle particles too large to pass the screens 88. The point at which body 'I8 and its assembly is located is immediately forward of the point at which the filter units 40 come over sprocket |32 to form a level floor. This relation may be seen in Figures l and 7a..

Wooden rails or bars 34 are provided to sit snugly at the outer edges of filter surfaces 88 so as to retain a liquid level over said surfaces. As may be seen by Figure 5, a mechanism is provided for adjusting the height of these bars and for locating them into position, once their height has been chosen. Eachv bar 34 is held by in clamp 32-33 wnich is in turn associated with a plate 3| upon which the clamp 32--33 is vertically adjustable. The clamp 32--33 together with plate 3| is mounted upon channel plate I6, the enclosed or outer side of which houses the adjusting and locating mechanism 28. As can be seen from Figure 5, the adjusting unit 28 has sliding pads 29 to hold a block 30 which is tapped for a squared-end adjusting screw 21. Shoulders 30h are fitted with gibs 29a for vertical movement through said block. Screw 2l, after being adjusted vertically with a wrench moves block 30 vertically, thereby lifting or depressing also plate 3|, clamp 32-33 and bond bar or rail 34. After suitable adjustment has been reached block 28 is tightened against plate I6 by means of the han-dwheel and screw. Figure 5 provides the best illustration of this construction. Rail 34 is provided with a water groove w in its lower surface to assist in bonding the bar to the plates 88.

Referring now to Figures 8 and 8a, the machine is provided at its lefthand end (see Figure 2-) with a rotary scraper |04 mounted upon a sprocket driven shaft |03. Below said scraper a flexible steel plate |06 ground to a tapered edge makes contact with the traveling screen surfaces 88 so as to shave off from them such oversized nodules of pulp as have not been able to pass the foraminous surfaces 8B. Plate |06 is bent up to follow the inclination of an arcuate apron |0| which forms a hump or dam |10 which is integral with a trough 89 in which a helical conveyor |09 is operated by a shaft |03. Scraper |04 operating at high speed throws the nodules shaved off by blade |06 over hump l0 into trough 89 where the rotation of conveyor |09 pushes such material toward a hopper |00 leading out of the machine.

Referring now to Figures 1 and 2, the matter shown here has to do with means of cleaning the surfaces 88 while they are inverted when the units 40 are traveling back to their starting point at the right side of the machine. As can be seen in Figure l1, a trough or apron extends beneath the machine and this trough is supplied with water through a shower pipe la. An exit pipe m' for refuse water is also provided. A liquid level extending well over the surfaces 88 is however maintained. Toward the left end of the machine there is a trough ||2 in which a brush roller H6, supported by bearings ||8 and driven by shaft HB, is located. This shaft is driven `by a sprocket |36. Baiiles ||3 and H are provided in trough which are so arranged as to provide maximum turbulence in the water. This arrangement can be seen in Figure l. In brief, a staggered path is provided for the water which flows in one direction above the baffles and in another direction under the baliles through space IIB. The flow under the baffles is toward exit pipe m. The rotation of brush 6 as seen in Figure 2 is counterclockwise. Contact of the brush roll H6 effectively removes material from the surfaces 88 which is too ne to have been removed by the blade |06.

Again referring to Figure 5, a screw adjustment is provided which comprises screw 10, nut 1| and socket 'l5 by which the rack S6 may be withdrawn out of contact with rollers 64. It is therefore possible to regulate the degree of shock produced by the Contact of rollers 64 with rack 66 or it is possible to separate these elements entirely so that there is no pumping actiony through the foraminous plates 68.

As is shown by Figures 2 and 4, sprocket |36, which drives the brush roll, is suitably placed for a motor to drive shaft H9. Drive is thenv by chain to sprocket |29 which in turn drives gear |30, meshing with gear |3| which drives sprocket |32, Sprocket |28 also mounted on shaft |21 which is common to sprockets |29, |28 and gear |38, also drives sprocket |33 which is mounted on shaft |3 which drives rotary scraper |64. A second sprocket |34 on shaft |03 carries a chain drive to sprocket |35, thereby turning shaft |68 to rotate helical conveyor IDS.

The operation of my device will be fully apparent from the above description to any competent pulp and paper engineer.

I claim:

1. In a pulp screen washer, a substantially rectangular frame, two sprockets rotatably mounted substantially at the corners of said frame at each end thereof, endless chains passing over opposite pairs of sprockets and adapted to operate in horizontal unison and alignment, a series of screening elements carried between said chains and closely spaced together, a slurry supplying box, a dam in said box and a cascade seal between said box and said series of screening elements, said seal being operative when said screening elements are substantially level, said box, dam and cascade seal being located at that end of the machine away from which the upper series of screening elements moves, means for maintaining a liquid level over said screening elements, a trough extending below said screening elements for discharging filtrate from the latter, a shaving blade, a rotary scraper and a crosswise disposed helical conveyor located behind said blade and scraper at that end of the machine opposite said slurry supplying box, said blade and scraper being disposed in operative relation to said series of screening units when the latter are level, to remove solid matter deposited upon them, said blade being arranged to deliver such solid matter to the scraper, the scraper to deliver it to the conveyor and the conveyor to remove it from the machine; a washing trough adapted to carry a water level and to receive said series of screening elements in inverted position during its traveling back to its starting point, a brush roll in contact with the screening surfaces of said screening elements to wash the latter clear of solid matter clogging their openings and baille means adapted to create water turbulence beneath the screening units while the latter are being washed and to direct resulting water containing solid matter in suspension back toward that end of the machine which lies under said slurry box.

2. In a pulp screen and washer, a substantially rectangular frame, pairs of identical sprockets at each end of said frame, a common axle for each pair of said sprockets, an endless chain running the length of the machine connecting opposite sprockets on different axles, a plurality of box-shaped screening elements extending crosswise of and being attached as to their ends to each chain, so as to be carried by said chains in unison While preserving accurate alignment from one chain to the other, at foraminous surfaces at the top of each screening unit, a discharge spout in the bottom of each screening unit at the lowest point thereof, a deformable strip between each screening unit and the next, said unit being adapted to act as a sealing means, said foraminous surfaces and said sealing units being adapted to cooperate to form a substantially fiat surface at some time in the travel cycle of said units, adjustable rail means extending Aacross the ends ,of the units forming said flat surface, said rails being adapted to maintain a liquid level above said foraminous surfaces as to the sides thereof, a cascade seal at the starting end of said flat surface, pulp spreading and supplying means adapted to supply pulp evenly over said pulp cascade seal, means for removing unfiltered pulp from the other end of said flat surface, means for eliminating pulp so removed from the machine, and a liquid receiving trough extending under said series of screening units when the latter are flatly arranged, the discharge spouts on said screening units extending into said trough, means for removing liquid from said trough and from the machine and washing means including a rotary brush roll for clearing the foraminous portions of said filtering units when in inverted position and traveling towards their starting point to again assume their position as parts of the said flat surface.

3. An individual screening unit adapted to be used in a pulp screen and washer of the character described which comprises a boxlike body, a foraminous at top for said body, a deformable strip on one longer edge of said foraminous top, a flexible bottom, a stiff plate centrally attached to said exible bottom, a roller leg extending downwardly from said stii plate, a spring mounting for said roller leg, a discharge spout at the lowest point of said flexible bottom, a deflector plate adapted to cooperate with said discharge spout to provide a liquid seal, said discharge spout having also in its region where the liquid seal is provided, a small by-pass opening, and attached to the ends of said boxlike body of the screening unit, two stepped shafts protruding from each of the ends of said body, the ends of said shafts being adapted to function as the link studs of a roller chain.

CARL SCHEIDING. 

